1. Field of the Invention
The present invention relates to an improved vehicle washing apparatus and, more particularly, to a vehicle washing apparatus having a conveyor with an improved roller assembly call up mechanism which includes an anti-jam feature.
2. Description of the Related Art
Various prior art vehicle washing installations and systems have heretofore been known and are in widespread use. The typical vehicle washing system includes a wash bay having a floor in which a conveyor is mounted for moving the vehicle through the installation and a series of power driven brushes and scrubber curtains are utilized to clean the vehicle under a drenching spray of water and cleaning agent. The washed vehicle is then given a drenching spray of clean rinse water and is dried.
A well known prior art conveyor is of the over and under type which utilizes an endless conveyor chain having a plurality of spaced roller assemblies attached along the length thereof. The endless chain typically extends around a three track structure comprised of a slotted upper track, an intermediate track and a lower track. The slotted upper track supports a vehicle such as a car. When the car advances on to the upper track, pusher rollers from a roller assembly are needed so a forked ramp is provided which is raised from the intermediate track to intercept and guide the pusher rollers through an opening roller assembly onto the slotted upper track along which the car tires roll. The pusher rollers then engage a tire of the vehicle to push the car through the washing installation. The slotted upper track accommodates the tire of a vehicle being washed and also provides a travel path for the pusher rollers which are selected at an appropriate time. The intermediate level track provides the forward track for the idle rollers of the roller assemblies as well as for unselected roller assemblies where the pusher rollers have not been ramped up to the slotted upper track and the lower track provides a return track for the roller assemblies.
A typical prior art over and under conveyor 10 is illustrated in FIGS. 1 and 2. The conveyor 10 includes a slotted upper track 12, an intermediate track 14 and a lower track 16.
The conveyor includes an endless chain 18 having a plurality of spaced roller assemblies 20 connected thereto. Each of the roller assemblies 20 has a pair of idler rollers 22 at its forward end and two pairs of pusher or tire engaging rollers 24 at its back end. The pusher rollers 24 engage the back of a tire 26 of a vehicle to push the vehicle along the slotted upper track of the conveyor in the direction indicated by the arrow A.
The conveyor is provided with an entrance trap door 28 at an entrance end thereof and with an exit trap door 30 at an exit end thereof.
A roller call up mechanism, generally indicated by the numeral 34, is provided at the front entrance end of the conveyor to move the pusher rollers 24 from a down position on the intermediate track to a raised tire engaging position on the slotted upper track to engage the tire of a vehicle after the vehicle has moved onto the conveyor.
The call up mechanism 34 is shown in greater detail in FIG. 2 and includes a power cylinder 36 having a rod pivotally connected to the crank arm 38 which in turn in fixedly secured to an outer end of an axle 40 which extends parallel to the slotted track in a direction perpendicular to the length thereof. A pair of spaced forks 42 are fixedly secured to the axle 40 for rotation therewith and form a ramp for moving the pusher rollers 24 up to the slotted upper track.
In operation of the typical prior art conveyor, when a vehicle has moved onto the slotted upper track of the conveyor, a signal is sent either manually by a call up button or automatically by a pressure sensing switch to the roller call up mechanism. This in turn activates the power cylinder 36 forwardly whereby crank arm 38 is rotated to rotate the axle 40. When the axle 40 is rotated, the forks 42 are raised upwardly. As a roller assembly is moved forwardly the pusher rollers engage the forks and are moved upwardly to push the trap door 28 open and to ride along the top of the slotted upper track to engage the back of a tire. The pusher rollers then move the vehicle down the track until reaching the end of the conveyor track whereupon the pusher rollers open the exit trap door 30 and drop back down to the lower track and loop back until a signal is again given causing the cycle of roller call up to start over again.
A problem with this type of this prior art conveyor is that if a car wheel is on top of the entrance trap door at the time the pusher rollers are ramped up by the forks, the rollers start to come up but stop below the trap door and jams up before emerging onto the slotted upper track. This sudden stop and jam up can cause serious damage to the conveyor chain and other components of the conveyor system. Therefore there is a need for an anti-jam device for the roller call up mechanism.